Known from practical use are parking brakes for motor vehicles which have a brake actuation lever arranged pivotably on a lever holder, a locking device comprising a toothing arranged on the lever holder and a locking catch engaging in the toothing, a coupling unit for coupling the brake actuation lever to a brake cable and a release device. In an embodiment of such parking brakes, the release device includes a push rod which can be displaced along the brake actuation lever between an inoperative position and a release position, wherein the locking catch is pivotably articulated to the push rod. The locking catch is in the form of a double lever with a first lever arm and a second lever arm, and is mounted pivotably on the brake actuation lever in a central region connecting the lever arms. On an end of the first lever arm oriented away from the central region the locking catch has an engaging dog for engaging in the toothing, the pivotable articulation of the locking catch to the push rod being provided on an opposite end oriented away from the central region. A spring element preloads the push rod with respect to the brake actuation lever in the direction of the inoperative position of the push rod, the engaging dog of the locking catch at the same time being preloaded by the preloading in the direction of the toothing. In order to operate the parking brake, the brake actuation lever is pivoted with respect to the lever holder so that the brake cable is pulled. In order to release the parking brake the push rod is moved from the inoperative position to its actuating position against the preloading of the spring element, the engaging dog of the locking catch at the same time being moved out of the toothing, which allows the brake actuation lever to pivot back to its starting position. In the motor vehicle parking brake described, the push rod is displaced with respect to the brake actuation lever against the preloading of the spring element in order to release the parking brake. Once the release process has ended the push rod, driven by the spring element, is moved back to its inoperative position, the push rod being subjected to an impact and to large mechanical forces at the end of the return movement to its inoperative position. Through an impact of the push rod in its inoperative position, firstly, disadvantageously undesired noises are caused and, secondly, parts of the release device arranged on the push rod are subjected to high mechanical stress. In particular if the parking brake is in the form of a handbrake, a release element in the form of a push button is subjected to high acceleration and/or to a very rapid change of acceleration over time, so that mechanical damage to the push button can occur.
DE 199 36 733 A1 describes a parking brake for a motor vehicle which comprises a brake actuation lever arranged pivotably on a lever holder, a locking device which has a toothing arranged on the lever holder and a locking catch, a coupling device for coupling the brake actuation lever to a brake cable, and a release device including a push rod which is displaceable along the brake actuation lever from an inoperative position to a release position. Here, the locking catch is also in the form of a double lever and is articulated pivotably to the brake actuation lever, an engaging dog arranged at the end of the first lever arm being preloaded in the direction of the toothing by a catch spring engaging on the end of the second lever arm. In this embodiment, the push rod of the release device is not connected pivotably to the locking catch but has on its end oriented towards the locking catch an impact region with which the push rod, in an actuating position of the locking catch, moves out of an engaged position, against the preloading of the catch spring, and displaces the engaging dog arranged on the second lever arm from the toothing. Through the lack of a coupling of the push rod to the locking catch in the inoperative position of the push rod, vibrations of the locking catch as it is displaced along the toothing are not transmitted to the push rod and therefore not to the interior of the motor vehicle. However, the disadvantage in this case also is that the return movement of the push rod, with its impact in the inoperative position, produces high mechanical stress on the push rod and components connected thereto, and disturbing noise is generated.
DE 101 27 505 A1 describes a parking brake for a motor vehicle with a locking device which includes a locking catch and a release device which includes a push rod. The locking catch is in the form of a double lever with a first lever arm and a second lever arm, an engaging dog for engaging in a toothing being arranged on the second lever arm. The first lever arm of the locking catch is guided at its end in a linking element, the end of the first lever arm passing through a slot arranged in the linking element. The end of the linking element oriented away from the slot is connected to a push rod, the push rod and the linking element being displaceable with respect to one another and being preloaded against one another by means of a first spring element. The push rod is preloaded in the direction of an inoperative position with respect to a brake actuation lever by means of a second spring element. In this embodiment also, high mechanical forces act on the push rod as it is moved from a release position to the inoperative position, whereby disturbing noises are likewise produced.